Abstracts - VGB PowerTech Journal 4/2017
Editorial: Combining heat and power – generating double benefits
Dr.-Ing. Oliver Then
The energy and power generation industries in Germany, in Europe and worldwide are in a state of transition. The process of transformation in the energy system has reached a critical phase, characterized by the integration and dominance of renewable energy sources and the associated growing and changing requirements for the whole electricity supply system. The “three Ds” of the target triangle in electricity supply accurately describe what is happening. [more...]
Large-scale storage options under special consideration of 6 x 15 MW battery example
Wolfgang A. Benesch and Christian Karalis
The renewable share in electricity generation is growing fast. But this kind of electricity is unfortunately often not produced in the right location and/or at the appropriate time. Coming back to technical and economical boundary conditions, different solutions can be discussed. This could be solved by efficient coal fired power stations. As well gas fired combined cycle plants can help. A total different answer is given by storage systems. In that case different technologies and their pros and cons have to be considered. How far are they for example able to bridge the so called dark slack? Also in this case, new technologies like battery systems, can take additional responsibilities to support the extension of renewables. In this field the development is quite fast and the products are ready for the market.
Grid development and system security in times of the “energy turnaround” – Status quo and further development of the electricity supply system
Tino Schlemmer, Uwe Schmidt and Wolf-Dieter Diebels
Liberalisation of the power market and consistent extension of renewable power generation inducing step-by-step significant system changes from central structure with unidirectional load flows onto decentral structure with bidirectional load flows. The politically forced consistent extension of renewable power generation is the substantial driving force for necessary grid extension for big energy transfers over long distances. Grid extensions are based on the “Netzentwicklungsplan” to be developed by the TSO and to be approved by the Bundesnetzagentur (BNetzA). BNetzA has approved new routes and strengthening measures representing a total length close to 6,000 km including three North-South-connections in HVDC technology having transfer capacities of 2 GW each. HVDC connections shall be realised.
40 Years of Circulating Fluidised Bed (CFB) power plant technology – A review of the history, present status and future potential of the application of an innovative and successful combustion technology
Damian Goral, Reinhard Knittel, Silvio Löderbusch, Hans Piechura and Ludolf Plass
The power plant technology using the fluid-mechanical principle of the circulating fluidised bed (CFB) was, based on its advantages in terms of emissions control and fuel flexibility a huge success, as proven by almost 5,000 references around the world. Starting with the initial installations the development from stationary to circulating fluid beds is described and its roots in metallurgical applications are shown. From the first ideas of the inventors, the development from pilot scale up to utility size plants is reviewed. Consequently also alternative and competing concepts are listed as well as the developments on the Chinese market. The developments are verified with examples of executed references and operating data. The second part of the technical paper focuses on state-of-the-art and future concepts of CFB power plant applications. Apart from the examples for innovative plant arrangements, concepts with super-critical and ultra-super-critical steam parameters are introduced, as well as applications for biomass combustion. Finally a concept of the integration of a CFB power plant into an innovative energy model is presented as an example of applications resulting from the energy transition.
Innovative concepts for flexibilisation of power plant operation
Hellmuth Brüggemann, Frank Kluger and Gerald Schmidt
Renewable energy sources play an growing role and the share of photovoltaic and wind power generation is increasing rapidly. As this source of energy is highly fluctuant and cannot be controlled by the grid dispatchers, the conventional fossil power plants have to compensate these fluctuations to stabilise and secure the grid. Conventional plants have to operate in mid to low loads and will face more cold, warm and hot start-ups, consuming significant amounts of expensive oil instead of more economical coal. This brings the conventional power plants to an even more challenging economic situation, especially if more and more renewable energy sources are contributing to the public power grid. New developments of GE help starting fossil power plants by using coal as a start-up fuel. The newly developed system uses plasma technology to directly ignite the fuel. Tests have been conducted at several test facilities and have successfully demonstrated the solid fuel ignitions system is fulfilling the task reliably and safely.
Large scale, high efficiency biomass power plant with fluidised bed combustion in Europe
Teemu Nevalainen, Timo Eriksson and Kalle Nuortimo
Major incentives on renewable power and decreasing consumption have nearly stalled thermal power investments in Europe. While fossil fuels are facing strong political pressures there seems to be market for CO2 neutral thermal power as well as CHP production. Today’s market situation calls for fuel flexible technologies, while maximum efficiency and economics of scale drive towards utility size solutions. Fulfilling the above-mentioned boundary conditions, a contract awarded for biomass power project in U.K. is taking the Circulating Fluidised Bed (CFB) combustion technology to the 300-MWe scale with sole biomass fuels. When this CFB boiler enters commercial operation in January 2020, it will be the world’s largest and most advanced 100% biomass fired CFB.
Converting CFB boilers from coal to 100 % biomass combustion
Jan Žižka , Ludvík Pavlík and Hynek Lang
With the requirement to increase the share of renewables in the Czech republic there is aim as much as possible to utilise biomass for electricity generation. Scheme of subsidy was created with the different levels according to type of biomass and type of combustion. ?EZ, a.s. evaluated this opportunity and decided to refurbish circulated fluidised bed boilers at Power Plant Po?í?í and Power Plant Hodonín. Refurbishments enable to increase amount of biomass to be burnt in combustion chamber from 25 % to 100 % of heat value in fuel.
Optimisation potentials of drying and heating of refractory linings
Matthias Trost, Hans Joachim Sauer and Michael Evard
The situation on the energy market forces operators of power plants to operate their plants much more flexible and at lower costs. The fire-resistant lining is important because higher load-cycling gradients can lead to a conflict with predefined heating-up and heating-off gradients of the material. Solutions are presented, how the efforts required for proper drying can be limited or reduced, in order to shorten the duration of commissioning of a boiler. These include the optimisation of temperature monitoring and the resulting optimised heating curves, the use of optimised materials as well as the possibilities of dry heating. An example is presented in detail.
Challenges in coal-fired energy production in Europe
Joachim Feuerborn and Ivan Skidmore
About one fourth of the European energy production is based on fossil fuels. The production in these power plants is under continuous pressure to meet legal requirements for clean air and market requirements regarding availability and economic production. The energy strategies of the European Commission require CO2 reduction, increased production by renewables and energy savings. For grid stability coal-fired stations serve increasingly in non-continuous backup operation with economic risk in production of by-products and lifetime of installations. In Europe, the energy production by coal still results in more than 145 million tonnes of Coal Combustion Products (CCPs) each year. Most of these CCPs are used as replacement for natural occurring raw and construction materials with environmental benefits in mining and production as well as increased durability of the constructions.
Special challenges for hydraulic components in safety related applications
Dirk Bracht
Many processes in the chemical engineering take place under high temperatures and pressures. To secure the necessary technical processes and avoid all negative effects for people, the environment and technology due to external interference and accidents in the plant; shut-off-, control- and safety valves are installed. These valves must operate reliably in a consistent manner. This reliability is primarily endangered because during long times of non-actuation of safety valves, no oil exchange takes place in the pipes and components. The Self-Testing Switching System STSS ? an intelligent monitoring system for safety related applications is new developed to achieve the goal of a continuous operational reliability. It is independent of the vendor diversity in plant use, can run any operating cylinder, test the system and prevent the resin from forming and the silting effect by regular exchange of oil without interruption or interference of the plant operation.
Multi stage vacuum membrane distillation, an innovative solution for water processing in power plants
Christian Hüttl, Herbert Fahrnbauer and Christoph Maurer
An efficient water management is of great interest for the operation of combined cycle power plants. Especially in arid regions a decreased water consumption of power plants is important. Today several strategies to avoid waste water are already applied. A further reduction of the waste water streams could be achieved by treatment of the still occurring waste water streams. The vacuum multi effect membrane distillation is an energy efficient technology to process waste water which has been characterised in extensive experiments. The technology is able to produce distillate which fulfils the current regulations out of boiler blow down water. Hence the vacuum multi-effect membrane distillation is suitable to process a significant part of the waste water from a power plant and provide demineralised water which can be used in the water steam cycle.